/* Copyright © 2023 - 2024 Coremail论客
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import util from '@ohos.util';
import { CMError, ErrorCode } from '../api';
import { getLogger } from '../utils/log';

/**
 *
 */
enum CompressedRtfType  {
   Compressed = 0x75465A4C,
   Uncompressed = 0x414C454D
}


export class CompressedRtfHeader {
  static headerSize:number = 0x10

  init(u8a:Uint8Array) {
    if(u8a.length < CompressedRtfHeader.headerSize) {
      throw new CMError(`[compressed_rtf_decoder] [length is not valid]`, ErrorCode.PARSE_RTF_FAILED)
    }
  }
}

 const Crc32Table:Uint32Array = new Uint32Array(
  [
    0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419,
    0x706AF48F, 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4,
    0xE0D5E91E, 0x97D2D988, 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07,
    0x90BF1D91, 0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
    0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7, 0x136C9856,
    0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
    0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4,
    0xA2677172, 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
    0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3,
    0x45DF5C75, 0xDCD60DCF, 0xABD13D59, 0x26D930AC, 0x51DE003A,
    0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423, 0xCFBA9599,
    0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
    0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190,
    0x01DB7106, 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F,
    0x9FBFE4A5, 0xE8B8D433, 0x7807C9A2, 0x0F00F934, 0x9609A88E,
    0xE10E9818, 0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
    0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E, 0x6C0695ED,
    0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
    0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3,
    0xFBD44C65, 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
    0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A,
    0x346ED9FC, 0xAD678846, 0xDA60B8D0, 0x44042D73, 0x33031DE5,
    0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA, 0xBE0B1010,
    0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
    0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17,
    0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6,
    0x03B6E20C, 0x74B1D29A, 0xEAD54739, 0x9DD277AF, 0x04DB2615,
    0x73DC1683, 0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
    0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1, 0xF00F9344,
    0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
    0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A,
    0x67DD4ACC, 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
    0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1,
    0xA6BC5767, 0x3FB506DD, 0x48B2364B, 0xD80D2BDA, 0xAF0A1B4C,
    0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55, 0x316E8EEF,
    0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
    0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE,
    0xB2BD0B28, 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31,
    0x2CD99E8B, 0x5BDEAE1D, 0x9B64C2B0, 0xEC63F226, 0x756AA39C,
    0x026D930A, 0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
    0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38, 0x92D28E9B,
    0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
    0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1,
    0x18B74777, 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
    0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45, 0xA00AE278,
    0xD70DD2EE, 0x4E048354, 0x3903B3C2, 0xA7672661, 0xD06016F7,
    0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC, 0x40DF0B66,
    0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
    0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605,
    0xCDD70693, 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8,
    0x5D681B02, 0x2A6F2B94, 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B,
    0x2D02EF8D
  ]);



export class CompressedRtfDecoder {

   static  Prebuf:string =
    "{\\rtf1\\ansi\\mac\\deff0\\deftab720{\\fonttbl;}" +
      "{\\f0\\fnil \\froman \\fswiss \\fmodern \\fscript " +
      "\\fdecor MS Sans SerifSymbolArialTimes New RomanCourier" + "{\\colortbl\\red0\\green0\\blue0\n\r\\par " +
      "\\pard\\plain\\f0\\fs20\\b\\i\\u\\tab\\tx";
   static Compressed = 0x75465a4c;
   static Uncompressed = 0x414c454d;

  static _compressedRtfPrebuf:Uint8Array = null;

  //解压缩.
  public static decompress(src:Uint8Array):Uint8Array|null {
    let dst:Uint8Array = null;
    let inPos = 0;
    let outPos = 0;

    let encoder = new util.TextEncoder();
    // 207
    CompressedRtfDecoder._compressedRtfPrebuf = encoder.encodeInto(CompressedRtfDecoder.Prebuf);

    if(src == null || src.length <= 16) {
      // throw "Invalid compressed-RTF header";
      return null;
    }
    //src total 21579
    // 71 84 00 00    21575 = 21579 - 4
    //little-endian  高字节存放低位     数字排列顺序从高到底,是正常顺序.
    let compressedSize = new DataView(src.buffer).getInt32(inPos,true);
    inPos += 4;
    let uncompressedSize = new DataView(src.buffer).getInt32(inPos,true);
    inPos += 4;
    let compType = new DataView(src.buffer).getInt32(inPos,true);
    inPos += 4;
    let crc32 = new DataView(src.buffer).getInt32(inPos,true);
    inPos += 4;

    //process the data
    switch (compType) {
      case CompressedRtfDecoder.Uncompressed: {
        //复制inPos到结尾.
        dst = src.slice(inPos);
        break;
      }
      case CompressedRtfDecoder.Compressed:
        if(compressedSize != src.length - 4) {
          throw new CMError("compressed-RTF data size mismatch", ErrorCode.PARAMETER_ERROR);
        }
        if(crc32 != CompressedRtfDecoder.CalculateCrc32(src,16,src.length-16)) {
          throw new CMError("compressed-RTF CRC32 failed", ErrorCode.PARSE_RTF_FAILED);
        }
        dst = new Uint8Array(CompressedRtfDecoder._compressedRtfPrebuf.length + uncompressedSize);
        for(let i = 0; i < CompressedRtfDecoder._compressedRtfPrebuf.length;i++) {
          dst[i] = CompressedRtfDecoder._compressedRtfPrebuf[i];
        }
        outPos = CompressedRtfDecoder._compressedRtfPrebuf.length;
        let flagCount = 0;
        let flags = 0;
        while(outPos < dst.length) {
          flags = flagCount++ %8 == 0 ? src[inPos++] : flags >>> 1;
          if((flags & 1) == 1) {
            let offset = src[inPos++];
            let length = src[inPos++];
            offset = (offset << 4) | (length >>> 4); // the offset relative to block start
            length = (length & 0xF) + 2; // the number of bytes to copy
            // the decompression buffer is supposed to wrap around back
            // to the beginning when the end is reached. we save the
            // need for such a buffer by pointing straight into the data
            // buffer, and simulating this behaviour by modifying the
            // pointers appropriately.
            offset = Math.floor(outPos / 4096) * 4096 + offset;
            if (offset >= outPos) // take from previous block
              offset -= 4096;
            // ReSharper disable once CommentTypo
            // note: can't use System.arraycopy, because the referenced
            // bytes can cross through the current out position.
            var end = offset + length;
            while (offset < end)
              dst[outPos++] = dst[offset++];
          }
          else {
            //literal
            dst[outPos ++] = src[inPos ++];
          }
        }
        break;
    }
    src = dst;
    //这里又舍弃掉了Prebuf,是否可以一开始就不用?
    dst = src.slice(CompressedRtfDecoder._compressedRtfPrebuf.length);
    return dst;
  }


  private static CalculateCrc32(u8a: Uint8Array, off: number, len: number): number {
    let c: number = 0;
    var end = off + len;
    for (var i = off; i < end; i++) {
      let index = (c ^ u8a[i]) & 0xFF
      c = Crc32Table[index] ^ (c >>> 8);
      // console.log(c.toString());
    }
    // console.log(c.toString());
    return c as number;
  }
}